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Low temperature stress during germination and early seedling growth is an important constraint of global production of maize. The effects of seed priming with 0.25%, 0.50%, and 0.75% (w/v) chitosan solutions at 15 degrees C on the growth and physiological changes were investigated using two maize (Zea mays L.) inbred lines, HuangC (chilling-tolerant) and Mo17 (chilling-sensitive). While seed priming with chitosan had no significant effect on germination percentage under low temperature stress, it enhanced germination index, reduced the mean germination time (MGT), and increased shoot height, root length, and shoot and root dry weights in both maize lines. The decline of malondialdehyde (MDA) content and relative permeability of the plasma membrane and the increase of the concentrations of soluble sugars and proline, peroxidase (POD) activity, and catalase (CAT) activity were detected both in the chilling-sensitive and chilling-tolerant maize seedlings after priming with the three concentrations of chitosan. HuangC was less sensitive to responding to different concentrations of chitosan. Priming with 0.50% chitosan for about 60 approximately 64 h seemed to have the best effects. Thus, it suggests that seed priming with chitosan may improve the speed of germination of maize seed and benefit for seedling growth under low temperature stress.

BackgroundThe low seed vigor and poor field emergence are main factors that restricting the extension of sweet corn in China. Spermidine (Spd) plays an important role in plant growth and development, but little is known about the effect of Spd on sweet corn seed germination. Therefore the effect of exogenous Spd on seed germination and physiological and biochemical changes during seed imbibition of Xiantian No.5 were investigated in this study.ResultsSpd soaking treatment not only improved seed germination percentage but also significantly enhanced seed vigor which was indicated by higher germination index, vigor index, shoot heights and dry weights of shoot and root compared with the control; while exogenous CHA, the biosynthesis inhibitor of Spd, significantly inhibited seed germination and declined seed vigor. Spd application significantly increased endogenous Spd, gibberellins and ethylene contents and simultaneously reduced ABA concentration in embryos during seed imbibition. In addition, the effects of exogenous Spd on H2O2 and MDA productions were also analyzed. Enhanced H2O2 concentration was observed in Spd-treated seed embryo, while no significant difference of MDA level in seed embryo was observed between Spd treatment and control. However, the lower H2O2 and significantly higher MDA contents than control were detected in CHA-treated seed embryos.ConclusionsThe results suggested that Spd contributing to fast seed germination and high seed vigor of sweet corn might be closely related with the metabolism of hormones including gibberellins, ABA and ethylene, and with the increase of H2O2 in the radical produced partly from Spd oxidation. In addition, Spd might play an important role in cell membrane integrity maintaining.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0951-9) contains supplementary material, which is available to authorized users.

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